One of the most common routes of administration for medications is by injection, such as intravenous, subcutaneous or intramuscular injection. A syringe containing the medication is used for the injection, which typically is carried out by trained medical personnel. In certain instances, a patient is trained in the use of the syringe to allow for self-injection. Moreover, certain medications are formulated in pre-filled syringes for patient use, to avoid the need for the patient to fill the syringe. Some patients, however, may be averse to carrying out self-injection, particularly if the patient has a fear of needles.
Automatic injection devices offer an alternative to a syringe for delivering a medication. Automatic injection devices have been used, for example, to deliver medications under emergency conditions, such as to administer epinephrine to counteract the effects of a severe allergic reaction, for example, as caused by a food allergy. Automatic injection devices also have been described for use in administering antiarrhythmic medications and selective thrombolytic agents during a heart attack (see e.g., U.S. Pat. Nos. 3,910,260; 4,004,577; 4,689,042; 4,755,169 and 4,795,433). Various types of automatic injection devices also are described in, for example, U.S. Pat. Nos. 3,941,130; 4,261,358; 5,085,642; 5,092,843; 5,102,393; 5,267,963; 6,149,626; 6,270,479; and 6,371,939.
In general, prior automatic injection devices, when operated, cause the needle of a syringe to move forward and project from a protective housing prior to actuation of the syringe to eject a dose of liquid through the needle. Movement of the syringe toward the patient's skin such that the needle is exposed before pressurizing a liquid charge inside the syringe helps prevent the liquid from dripping out of the needle before the actual injection takes place.
Such prior automatic injection devices have several disadvantages. For example, prior devices include an exposed needle that a patient is required to inject into him or herself, causing apprehension and anxiety for most patients, particularly those patients that are “needle phobic”. Prior devices are also difficult for patients to use, to maintain free of contamination, and/or to provide an accurate dosage of medicine. In addition, patients suffering from chronic autoimmune diseases such as rheumatoid arthritis, as well as the elderly and physically disabled, may lack the dexterity needed to self-administer biologic therapies using existing injection devices. A need therefore exists for such self-medication delivery devices that patients are able to use safely and that foster patient adherence to their biologic therapy regimens.
TNFα inhibitors are effective in the treatment of autoimmune disorders such as rheumatoid arthritis, psoriatic arthritis and Crohn's Disease. Such inhibitors, which include biological agents such as antibodies and antibody fusion proteins, typically are delivered by injection. The TNFα inhibitor adalimumab (HUMIRA®; Abbott Laboratories, Lake County, Ill.), for example, has been marketed as a pre-filled syringe for self-administration by patients and therefore presents as an important candidate for use with an improved automatic injection devices and methods.